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As with lines, curved boundaries may be allowed; usually a single feature may include multiple polygons, which OGC-SFA collectively terms a surface. Text (alternatively called annotation ): a minority of vector data formats, including the Esri geodatabase and Autodesk .dwg , support the storage of text in the database.
The shapefile format was introduced with ArcView GIS version 2 in the early 1990s. It is now possible to read and write geographical datasets using the shapefile format with a wide variety of software. The shapefile format stores the geometry as primitive geometric shapes like points, lines, and polygons.
In geographic information systems, a feature is an object that can have a geographic location and other properties. [1] Common types of geometries include points, arcs, and polygons. Carriageways and cadastres are examples of feature data. Features can be labeled when displayed on a map.
A simple vector map, using each of the vector elements: points for wells, lines for rivers, and a polygon for the lake A vector dataset (sometimes called a feature dataset) stores information about discrete objects, using an encoding of the vector logical data model to represent the location or geometry of each object, and an encoding of its ...
TIGER includes both land features such as roads, rivers, and lakes, as well as areas such as counties, census tracts, and census blocks. Some of the geographic areas represented in TIGER are political areas, including state and federally recognized tribal lands, cities, counties, congressional districts, and school districts.
A feature may or may not have geometric aspects. A geometry object defines a location or region instead of a physical entity, and hence is different from a feature. In GML, a feature can have various geometry properties that describe geometric aspects or characteristics of the feature (e.g. the feature's Point or Extent properties).
The origin of the geodatabase was in the mid-1990s during the emergence of the first spatial databases.One early approach to integrating relational databases and GIS was the use of server middleware, a third-party program that stores the spatial data in database tables in a custom format, and translates it dynamically into a logical model that can be understood by the client software.
The ARC/INFO Coverage data structure (1981), a topological data model based on POLYVRT. Topology was a very early concern for GIS. The earliest vector systems, such as the Canadian Geographic Information System, did not manage topological relationships, and problems such as sliver polygons proliferated, especially in operations such as vector overlay. [9]